Background The International Classification of Functioning, Disability and Health (ICF)1 is a reference framework to describe the impact of health conditions on functioning and disability. A Comprehensive and Brief ICF Core Set for osteoarthritis (OA) has been developed2 and must be statistically validated.
Objectives Our specific aims were (1) to identify ICF categories that best explain patients’ functioning, (2) to determine the content validity of the Brief ICF Core Set, and (3) to propose a statistically-validated version.
Methods Psychometric study using Group Lasso regression on data from a convenience sample of 879 OA patients from 20 countries. The subscale on general health of the SF-36 was used as dependent variable and all ICF categories of the Comprehensive ICF Core Set for OA and some socio-demographics and disease-specific characteristics as independent variables. The most relevant ICF categories were identified as those showing a significant effect based on the pointwise 90% confidence intervals resulting from 1000 bootstrap trials.
Results Based on our results, there were 15 ICF categories included in the statistically-validated version of the Brief ICF Core Set for OA: five body functions (sensation of pain, mobility of joint, muscle power, energy and drive, and emotional functions), three body structures (structure of upper extremity, structure of lower extremity, and additional musculoskeletal structures related to movement), three activities and participation (hand and arm use, walking, and dressing), and four environmental factors (products and technology for personal use in daily living, immediate family, health services, systems and policies, and societal attitudes). Twelve of the original 13 Brief ICF Core Set categories were confirmed, and three additional ICF categories were identified.
Conclusions Our findings reassure the validity of the Brief ICF Core Set for OA. The statistically validated Core Set (12 categories out of 13) with the additional three statistically-derived ICF categories will likely perform better with regard to discrimination and sensitivity to change in studies and trials, and should be further explored in the future.
World Health Organization. International Classification of Functioning, Disability, and Health. WHO: Geneva, 2001.
Dreinhöfer K, Stucki G, Ewert T, et al. ICF Core Sets for osteoarthritis. J Rehabil Med. 2004;(44 Suppl):75-80.
Disclosure of Interest None Declared